Electric switching device.



`lvl. L. SEVERY.

ELEcRlc swlTcHmG DEVICE.

APPLICATON FILED JULY B, IBIS.

Patented Mur. 6, 1917.

2 SHEETS-SHEET I nu, muws Perses :o nonnina wnsumurosv n c M. L. SEVERY.

ELECTRIC swlcHlNG DEVICE.

APPLICATION ILED IULY E. i913.

Patented Mar. 6, 1917.

2 SHETS-SHEET 2 .inverni/020;

Zwin/eases:

UNITED STATES PATENT OFFICE.

MELVIN L. SEVERY, 0F ARLINGTON HEIGHTS, MASSACHUSETTS, ASSIGNOR TO SEVERY MANUFACTURING COMPANY, 0F BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

ELECTRIC SWITCHING DEVICE.

Specification of Letters Patent.

Patented Mar. 6, 1917.

To all whom 'it may concern.'

Be it known that I, MELvIN L. SEVERY,

of Arlington Heights, in the county of Mid dlesex and State of Massachusetts, have invented certain new and useful Improvements in Electric Switching Devices, of which the following is a specification.

This invention relates to an improvement in circuit opening and closing devices.

One object of the invention is to provide a device for preventing all sparking, or all excessive sparking when a circuit is broken.

Another object of the invention is to provide means for preventing the sudden jerk of a magnet or solenoid when energized.

It has been found that when graphite and similar' compositions are used for electrical resistances, great care must be exercised in joining the graphite to the lead wire, for the reason that if this be not done there will be a high resistance at the point of junction which will entirely vitiate the computed resistance of the graphite. If the connection be made carelessly, the resistance, when measured, might be several times as great as the computed resistance, and this trouble would increase with the increase in the speciiic resistance of the material. Accordingly, one feature of the invention contemplates the utilization of the operation of a superficial contact to produce a high resistance, and the employment of this resistance when the circuit is broken to prevent excessive sparking. V

A further feature of the invention contemplates the provision of centrifugal means for retarding the operation. of the attractive force of an electromagnet or solenoid.

The invention will he readily understood from an inspection of the accompanying drawings, in which Figure 1 is a view partly diagrammatic and partly in sectional elevation, Fig. 2 is a pla-n view, Fig. 3 is a section taken on the line 3-3 in F ig. 1, Fig. 4 is a sectional elevation of one form of resistance element, Fig. 5 is a side elevation of another forni of resistance element, Figs. 6 and 7 are sectional and plan views, respectively of a resistance element arranged circularly, Figs. 8 and 9.are plan and side elevation, respectively, of a rectangularly arranged resistance element, and Fig. 10 is a side elevation of another form of resistance element.

As illustrated in the drawing, the device comprises a closed tubular receptacle 15, preferably of glass, which may be shaped like a letter J, mounted on a shaft 16 joue naled in suitable bearings 18, 19, said receptacle being partially filled with a conductlng Huid 20, preferably mercury. The receptacle may be exhausted, or it may contam air or be filled with a neutral gas. Mounted on the end of the short leg of the receptacle 15, is a resistance element or contact R, which may be any one of the various types to be hereinafter described, said element having its free end in proximity to a plate 22, extending across the receptacle and provided with an opening 24 and bleed holes 25 to prevent trapping of the liquid behind said plate. The opening 24 is preferably conlcal, and may be varied as desired in accordance with the rapidity with which the Huid 2O should pass therethrough. A plate 26 is hinged to the wall or plate 22 and acts asa flap valve, beingI provided with a couiparatively small opening 28, flaring outwardly, through which the liquid 20 passes when the receptacle 15 istilted into circuit closing position, said opening 2B being of such size and shape as to permit the liquid to pass therethrough withl the desired rapidity.

When the receptacle 15 is tilted up into circuit-closing position, the valve 26 is closed by the liquid 20, which then flows slowly through the opening 28 into contact with the resistance element R, thus produ@ ing a slight contact of high resistance at first, and gradually forming a greater contacting surface with attendant decrease in resistance. lVhen the receptacle is returned to circuit-opening position, the liquid 20 opens the valve 26 and thus effects a comparatively quick discharge of the same through the opening 24. Thus the resistance is quickly introduced, but with the desired rate of increase, dependent upon the size and shape of the opening 24, and also upon the structure of the element R, as will be more fully explained.

Mounted upon the side of the rece tacle 15 is a plate of insulating material 30,` upon which a pair of sector-shaped contact-members32, 33 are mounted. The member 32 is connected by a conductor 34 to the resistance element R, which is suitably supported within the receptacle 15, and the member 33 is connected by a conductor 36 to the plate 22. In Fig. 1 the conductor 36 is shown eX- tending through the wall'n of the receptacle 15 and connected to the plate 22, which forms the seat for the Hap valve 26. This conductor is shown broken olf in this figure but it extends between the plate 22 and the sector-shaped contact member 33. Apair of contact brushes 38, 39 engage the contactmembers 32, 33 andare-suitably supported in a block 40, said brushes being connected to conductors 41 and 42.

Any4 suitable means may be employed to tilt the receptacle 15, to make or break the circuit through the conductors 41 and 4.2. One means for performing this operation 1s a hand-lever 44, fastened on the shaft 16 and provided with a catch 46 for engaging a sector 48, to hold the receptacle in either position. A spring 50 is fastened at one end to the shaft 16, said spring being colled about said shaft and fastened at its other end in the bearing 18. This spring is put under tension when the receptacle is tilted to circuit-closing position, and returns to normal position when the shaft 16 is released.

Another means for controlling the operation of the device, comprises electro-responsive means adapted for remote control. Such means may consist of a solenoid 54 having a plunger 56, which is provided at its lower end with a rack 58 adapted to mesh with a gear 60 on the shaft 16. The solenoid 54, which may be of any of the well known forms, may be provided with an internal fixed core 57, which is adapted to contact with the upper end of the plunger 56 when the latter is drawn up into the coil 54.

The coil 54 is connected by a wire 62 to one end of a resistance 64, and the other end of said resistance is connected by a wire 66 to a switch-arm 68, said arm being pivot ed at 69 and connected by a wire 70 to one pole of a battery 72. The other pole of the battery is connected by a wire 74 to a fixed contact-member 76 of a circuit closer 77, said circuit closer having a movable contactmember 78, which is connected to the coil 54 by a`wire 80. A stationary switch contact-member 82, which coperates with the contact-member 83 on the switch-arm 68, is connected by a wire 84 to the Wire 62, thus forming a shunt around the resistance 64. The arm 68 has a projection 67 adapted to be engaged by a lug 71 on'the receptacle 15, to open the shunt circuit.

In order to prevent a sudden jerk by the solenoid at the moment of energization, I provide a screw threaded stem 90 on the upper end of the plunger 56, which engages a threaded nut 92 on a disk 94, to which centrifugally actuated levers 96, 97 are pivotally attached. These levers are preferably provided at their free e'nds with weights 98, 99, which may be wedgeshaped on their outer faces to engage a V-shaped groove 100 formed in the vertical fiange 102 of a plate 104. The weights 98, 99 are normally held out of engagement with the groove 100 by springs 106, which engage short arms 108 on the levers 96, 97. The disk 94 and nut 92 are preferably mounted upon an anti friction bearing 110, to insure ease of movement.

The operation of this circuit-controlling mechanism is as follows :-The circuit through the battery 72 is closed by the engagement of the contact-members 76. 78 of` the circuit closer 77, thereby energizing the coil 54 and drawing up its core 56. A too rapid upward movement of said core is pre'- vented by the centrifugally actuated Weights 98, 99, which engage the wall 102. The continued upward movement of the core 56 causes a rotation of the receptacle 15 into upright position, thus causing the liquid 20 to actuate the valve 26 and close circuit gradually through the resistance element R. lVhen the receptacle reaches its upright position the upper end of the core 56 engages the core 57, and the lug 71 engages and lowers the switch-arm 68. This opens the shunt circuit through 84, but the current passing through the resistance 64 is sullicient to energize the coil 54, so that the core 56 will be held up. When it is desired to break the circuit through the conductors.

41, 42, the contact-members 76, 78 are disengaged to break the circuit through the coil 54. Then the switch-arm 68 is released from the lug 71, the spring 73 draws said arm up to close this Switch.

The resistance element R may be constructed in various ways:-For exam ile, in Fig. 4 is shown a generally conical eiement 111, having its conical surface fiuted to a greater or less extent, but preferably without fiutes near its apex. This element may be composed of graphite, which is electroplated at its upper end and fitted with a metallic cap 112, preferably of iron. This cap may be formed with several internal annular ribs 114 to increase the surface contact between the cap and resistance material, said contact being made intimate as possible between the electroplated coating and the metal cap. A stem 116 is provided on the cap, to which a wire may be connected in any suitable manner.

As shown in Fig. 5, the resistance element may consist of a conical mass of resistance material 118, which is of varying specific resistance, that is, the ingredients of the material are such that the specific resistance is highest at the apex of the cone, and gradually diminishes toward its base. This, like Fig. 4, may be more or less fluted Where desired. A metal cap 120 is afiixed to the base of the cone and may be provided with an escalloped edge 122, to provide a gradually varying surface of metal contact when the element is immersed in or Withdrawn from a conducting liquid.

In Figs. 6 and 7 are shown a resistance elementconsisting of a plurality of conical members 124, composed of resistance material, as described above, and suitably mounted in intimate contact with a metal cap 126. These conical members may be Aarranged in concentric circles and vary in length either radially or circumferentially, or both; and the cap 126 is provided with apertures 128 extending therethrough, to allow a free passage` of the liquid therethrough, and to prevent trapping of air or gas when the inclosing receptacle contains such fluid.

As illustrated in Figs. 8 and 9, the resistance element may be composed of a rectangular cap 130, having parallel rows of conical members 132. composed of resistance material, and intimately1 connected to the cap 13() as explained above. This cap is also provided with apertures 13-1 to enable the conducting liquid to pass readily therethrough and prevent trapping of the same or any gas where the receptacle contains such.

As shown in Fig. 10 the resistance element may be composed of a cylindrical member 140, having a low-resistance portion 141 and a high-resistance portion 142, these portions tapering gradually in opposite directions, so that the resistance decreases gradually from the free end of the element toward the cap 141, which cap is affixed as described above. and may have a serrated edge 146 to vary more gradually the extent of metal contact When immersed in a liquid.

Thus in each of the elements enumerated above the resistance may be highest at the apex or enterin end of the element, and gradually diminish toward the other end, and at the same time in the conical elements the area of the surface contact is gradually increased as the element is immersed, and vice versa. In some instances the specific resistance of the element may be constant, but the superficial area of contact varies.

I claim:

1. AAsWitching device, comprising al receptacle containing a conducting liquid; a resistance contact having a varying resistivity in successive portions thereof; and

means whereby said liquid and contact may be moved relatively to each other to vary the resistance in the circuit by the resulting conjoint variation of the area of contact and the resistivity.

2. A switching device comprising in combination a movably mounted receptacle; a resistance contact having a resistivity progressively varying throughout the body thereof mounted in said receptacle; a conductive fluid contained in said receptacle and adapted when fiowed into Contact with said resistance contact to complete an electric circuit; and means for shifting said receptacle to cause said liquid to flow progressively into contact with an increasing area of said resistance contact, the direction of such increase in area of contact coinciding generally with the direction of variation of resistivity of said contact.

3. A switching device comprising in combination a movably mounted receptacle; a resistance contact having a resistivity progressively varying throughout the body thereof mounted in said receptacle; a conductive fluid contained in said receptacle and adapted when flowed into contact with said resistance contact to complete an electric circuit; means for shifting said receptacle to cause said liquid to How progressively into contact with an increasingI area of said resistance contact. the direction of such increase in area of contact coinciding generally with the direction of variation of resistivity of said contact; and means for retarding the circuit-closing How of said liquid.

l. A switching device comprising in combination a receptacle formed with two chambers; a valve structure adapted to open freely to How from the first to the second chamber and to close against reverse llow, but provided with a restricted b v-pass to permit such reverse flow; a resistance contact having a varying resistivity in successive portions thereof, mounted in said first chamber; a conducting liquid contained in said receptacle and adapted when in said first chamber to complete an electric circuit with said resistance contact; and means `tor alternately shifting said receptacle to cause said liquid to flow from one chamber' to the other.

5i. A switching device. comprising a resistance contact of varying specific resistance and a liquid in which said contact may be immersed, said contact and liquid being arranged for relative movement so that as the supercial contact between said liquid and contact varies the specific resistance of Athe immersed portion varies.

G. A switching device, comprising a conil 10 specific resistance progressively varying in the direction of its length and means for producing a progressive immersion of said Contact in the direction of its length in said liquid.

In testimony whereof I have affixed my 15 signature in the resence of two witnesses.

ELVIN4 L. SEVERY.

Witnesses: Q

EDWARD S. Cnocxn'r'r, WILLIAM J. SPERL. 

